The present invention relates to the apparatus of a rotary regenerative air preheater. More particularly, the invention relates to the sector plate assemblies of an air preheaters.
A rotary regenerative air preheater transfers sensible heat from the flue gas leaving a boiler to the entering combustion air through regenerative heat transfer surface in a rotor which turns continuously through the gas and air streams. The rotor, which is packed with the heat transfer surface, is divided into compartments by a number of radially extending plates referred to as diaphragms. These compartments are adapted to hold modular baskets in which the heat transfer surface is contained.
The air preheater is separated into a flue gas side or sector and one or more combustion air sides or sectors by sector plates. Conventional sector plate assemblies include numerous component parts, including multiple support ribs which are mounted to the backside of the seal plate for pressure stiffening. When completely assembled and welded together, the assembly forms an extremely stiff and rigid structure. The seal plate is then machined to a required flatness to attain the close sealing tolerances which are required. The sector plate assembly is costly because of the extensive machining required and the rigid nature of the sector plate assembly structure.
Briefly stated, the invention in a preferred form is a sector plate for an air preheater including a seal plate having a sealing surface and an oppositely disposed mounting surface. Multiple tabs mount a portion of a rigid support structure to the mounting surface of the seal plate. Multiple support members mount the support structure to the air preheater.
The support structure includes first and second side support ribs, which extend longitudinally from the inner end of the seal plate to the outer end of the seal plate, a single center support rib, which extends longitudinally from the outer end of the seal plate to a position intermediate the inner and outer ends of the seal plate, and multiple lateral support ribs. The tabs mount the lateral support ribs and the center support rib to the mounting surface of the seal plate and the side support ribs are welded to the seal plate. Each of the tabs has a first end portion welded to the support structure and an oppositely disposed second end welded along its full length to the mounting surface of the seal plate. The support members are mounted to each of the lateral support ribs adjacent one of the side support ribs.
Preferably, there are two inner lateral support ribs and four outer lateral support ribs. The inner lateral support ribs extend from the first side support rib to the second side support rib. A first pair of the outer lateral support ribs extend from the first side support rib to the center support rib and a second pair of the outer lateral support ribs extend from the second side support rib to the center support rib. The ends of the inner lateral support ribs are welded to the first and second side support ribs, the ends of the first pair of outer lateral support ribs are welded to the first side support rib and the center support rib, and the ends of the second pair of outer lateral support ribs are welded to the second side support rib and the, center support rib.
It is an object of the invention to provide a sector plate having a reduced number of structural parts.
It is also an object of the invention to provide a sector plate which requires less welding during construction.
It is further an object of the invention to provide a sector plate which requires no machining of the seal surface.
Other objects and advantages of the invention will become apparent from the drawings and specification.
The present invention may be better understood and its numerous objects and advantages will become apparent to those skilled in the art by reference to the accompanying drawings in which:
FIG. 1 is a general perspective view of a conventional bisector rotary regenerative air preheater which is cut-away to show the upper sector plate assemblies.
FIG. 2 is a simplified top view of a conventional trisector air preheater showing the rotor in the housing and showing the sector plate assemblies.
FIG. 3 is a top view of a conventional sector plate assembly.
FIG. 4 is a side view of the sector plate assembly of FIG. 3.
FIG. 5 is a bottom perspective view of the sector plate assembly of FIG. 3.
FIG. 6 is a top view of a low-distortion sector plate assembly in accordance with the invention.
FIG. 7 is a side view of the sector plate assembly of FIG. 6.
FIG. 8 is a bottom perspective view of the sector plate assembly of FIG. 6.